Electromagnetic reciprocating fluid pump



y 1968 H. F. ELLIOTT 3,381,623

ELECTROMAGNETIC RECIPROGATING FLUID PUMP Filed April 26, 1966 United States Patent 3,381,623 ELECTROMAGNETIC RECIPROCATKNG FLUID PUMP Harold F. Elliott, 800 Westridge Drive, Menlo Park, Calif. 94026 Filed Apr. 26, 1966, Ser. No. 545,335 2 Claims. (Cl. 103-152) I ABSTRACT OF THE DISCLOSURE An electromagnetic reciprocating fluid pump comprises a cylindrical pump chamber of nonmagnetic material. The lower flat wall of the chamber is in the form of a resilient diaphragm sealed to the cylindrical wall around its periphery, the diaphragm being of high-remanence paramagnetic material magnetized radially from its center outward. Below the diaphragm is a solenoid comprising a central core and a cup-shaped magnetic member forming essentially a closed magnetic path including the diaphragm. The upper wall of the pump chamber includes inlet and outlet ports, each having a one-way check valve. The solenoid winding comprises reactance means forming a part of a resonant circuit which, with an associated electronic valve, forms a source of periodic or pulsating unidirectional current for vibrating the diaphragm to pump fluid supplied to the inlet port.

This invention relates to electromagnetic reciprocating fluid pumps and, while it is of general application, it is particularly adapted for use in the fuel system of an automobile.

Heretofore there have been proposed and marketed a number of types of electromagnetic fluid pumps. In general, these have comprised a reciprocating solenoid core which either actuated a resilient bellows or diaphragm or served a dual function as a piston of a piston-type pump. Substantially all of the solenoid operated pumps have performed the fluid intake operation upon excitation of the solenoid and simultaneously compressed a spring, the latter performing the pumping stroke upon deenergization of the solenoid. Substantially all devices of this type have included some form of a lost-motion switch for cyclically energizing and deenergizing the solenoid from a direct-current source.

Electromagnetic reciprocating pumps of the type described have a number of disadvantages, among which may be mentioned a substantial amount of friction arising from the moving solenoid core or the pump pistons, or both; arcing and wear of the solenoid switch contacts; and an objectionable level of noise.

It is an object of the invention, therefore, to provide a new and improved electromagnetic reciprocating fluid pump which obviates one or more of the above-mentioned disadvantages of prior art pumps of the type described.

It is another object of the inventionto provide a new and improved electromagnetic reciprocating fluid pump which is simple, economical, and rugged in construction and embodies a minimum number of movable parts.

In accordance with the invention, there is provided an electromagnetic reciprocating fluid pump adapted to operate from a source of periodic current comprising a fluid pump chamber of nonmagnetic material having inlet and outlet ports, a one-way check valve registering with each of the inlet and outlet ports, a resilient diaphragm of paramagnetic material forming one wall of the pump chamber and sealed thereto around its periphery, a solenoid mounted adjacent the diaphragm and adapted to be energized from said source, and a magnetic core member for the solenoid including a central pole piece closely spaced from the center of the diaphragm in its undeflected position and portions completing a magnetic circuit between such pole piece and the periphery of the diaphragm.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description, taken in connection with the accompanying drawing, while its scope will be pointed out in the appended claims.

The single figure of the drawing is a cross-sectional view of an electromagnetic reciprocating fluid pump, together with a unitary source of periodic current, embodying the invention.

Referring now more particularly to the drawing, there is represented an electromagnetic reciprocating fluid pump adapted to operate from a source of periodic current and comprising a fluid pump chamber 10 of nonmagnetic material having an inlet port 11 and an outlet port 12. The pump chamber 10 is shown as a composite structure comprising a base plate 13 disposed adjacent a frame member 14 but separated therefrom by a gasket 15. The pump chamber 10 further includes an annular wall member 16 of channel-shaped cross-section sealed to the base plate 13 by way of an annular gasket 17 and secured thereto in any suitable manner as by a series of machine screws 18.

The fluid pump of the invention further comprises a one-way check valve registering with each of the ports of the pump chamber 16. By way of example, the inlet check valve comprises a sheet or flap 19 of resilient material, such as rubber, having a central portion normally closing the inlet port 11 and a series of apertures 19a surrounding the central portion and providing fluid passage when the flap 19 is released from the inlet port 11 during operation of the pump. The flap 19 is retained in position by an annular clamp 20 secured to the base plate 13 as by machine screws 21. The check valve for the outlet port 12 comprises a similar apertured resilient sheet or flap 22 having a central portion normally closing the outlet port 12 and secured to the annular chamber wall 16 by a clamp 23 secured to the member 16 by any suitable means (not shown).

The fluid pump of the invention further comprises a resilient diaphragm 24 of paramagnetic material sealed to the chamber wall member 16 around its periphery and forming one wall of the pump chamber 10. The seal between diaphragm 24 and member 16 may be a gasket (not shown) similar to gasket 17, a resilient O-ring, or equivalent sealing element. The diaphragm 24 may be of high-remanence paramagnetic material, such as a cobalt or chrome alloy steel, permanently magnetized radially from its center outward. Alternatively, the diaphragm 24 may be of low-remanence high-permeability material such as low carbon steel.

The fluid pump of the invention further comprises a solenoid, represented schematically at 25, and mounted adjacent the diaphragm 24 and adapted to be energized from a source of periodic current described hereinafter. The solenoid is provided with a magnetic core member 26 having a central pole piece 26a closely spaced from the diaphragm 24 in its undeflected position. The core member 26 further comprises portions completing a magnetic circuit between the pole piece 26a and the periphery of the diaphragm. Specifically, the core member 26 may be cup-shaped, as shown, enclosing the solenoid winding 25 and completing the magnetic circuit therefor around the entire periphery of the diaphragm 24. The pump chamber 10 and its associated actuating solenoid may be of any desired configuration but, in the most simple form, they are circular in a plane transverse to the plane of the sectional drawing.

Preferably, the solenoid winding 25 forms a part of the source of periodic current for the pump, specifically, part of an inverter circuit energized from direct-current supply teminals 27, 28 which may be energized from any suitable source such as a battery 29. The solenoid winding 25, the inductance of which is represented by the dotted-line inductor 25a, is connected in parallel with a reactance means such as capacitor 30 which forms with the solenoid 25 a resonant circuit. There is also provided an electronic valve such as a transistor 31 having input and out-put electrodes coupled through the resonant circuit 25, 30. Specifically, the base of transistor 31 is connected via a coupling capacitor 32 to one terminal of the winding 25, the emitter of transistor 31 is connected via coupling capacitor 33 to an intermediate terminal of the winding 25, while the collector of transistor 31 is connected directly to the other terminal of the winding 25. The output electrodes, that is, the emitter and collector of transistor 31, are connected to the supply terminals via a switch 34 and the solenoid winding 25. With the connections described, the winding 25, the capacitor 30, and the transistor 31 comprise a conventional oscillator circuit in which the base-emitter circuit and the collector-emitter circuit are regeneratively coupled through the resonant circuit 25, 30, so that these circuit elements form a conventional source of periodic current for the pump. If desired, an output terminal 35 may be connected to supply terminal 27 via switch 34.

It is believed that the operation of the electromagnetic reciprocating fluid pump of the invention will be apparent from the foregoing description. In brief, upon closing of the switch 34, the oscillator comprising transistor 31 and the resonant circuit 25, 30 with their interconnections generates a periodic current of a frequency depending upon the resonant frequency 'of the circuit 25, 30. This periodic current, flowing through the winding 25, produces an alternating magnetic field in the core member 26, the magnetic circuit for this field including the paramagnetic diaphragm 24. If the diaphragm 24 is permanently magnetized, as mentioned above, the device acts as a dynamic reciprocating motor, the diaphragm 24 being alternately attracted to and repelled from the center pole piece of the core 26. When the diaphragm 24 is at tracted toward the pole piece 261:, the pressure in the pump chamber is lowered, releasing the flap valve 19 from the inlet port 11 and drawing fluid into the pump chamber. When the diaphragm 24 is repelled from the pole piece 26a, the fluid in the pump chamber 10 tends to be compressed, closing the flap valve 19 and opening the flap valve 22 and expelling fluid through the outlet port 12. This cycle, of course, repeats at the frequency of periodic current developed by the oscillator described. The amplitude of deflection of the diaphragm 24 will be rather small but, due to the frequency of its vibration, an adequate volume of fluid will be pumped by the device.

In case the diaphragm 24 is of high-permeability low-' remanence material, the diaphragm will be attracted to the pole piece 26a during both the positive and negative half cycles of the magnetic field and during the portions of the cycle where the fluid is reversing, the diaphragm 24 will spring away from the pole piece 26a by its own resilience. The operation of the pump is essentially that described above except that the frequency of vibration of the diaphragm 24 is now twice the frequency of the periodic current generated by the oscillator.

In the event that the electromagnetic pump of the invention is used as a fuel pump in an automobile, the switch 34 may be a part of, or unicontrolled with, the ignition switch supplying a source of ignition voltage to the output terminal 35, in this case the battery 29 being the car battery.

While there has been described what is, at present, considered to be the preferred embodiment of the invention, it- Will be obvious to those skilled in the art that various changes and modifications may be made therein, without departing vfrom the invention, and it is, therefore, aimed in the appended claims to cover all such changes and modifications as fall Within the true spirit and scope of the invention.v

What is claimed is:

1. An electromagnetic reciprocating fluid pump adapted to operate from a source of pulsating unidirectional current comprising:

a fluid pump chamber of nonmagnetic material having inlet and outlet ports;

a one-way check valve registering with each of said ports;

a resilient diaphragm forming one wall of said chamber and sealed thereto around its periphery, said diaphragm being constructed of high-remanence paramagnetic material magnetized radially from its center outward;

a solenoid mounted adjacent said diaphragm and adapted to be energized from said source;

and a magnetic core member for said solenoid including a central pole piece closely spaced from said diaphragm in its undeflected position and ortions completing a magnetic circuit between said pole piece and the periphery of said diaphragm.

2. An electromagnetic reciprocating fluid pump in accordance with claim 1 including direct-current supply terminals, reactance means forming with said solenoid a resonant circuit, and an associated electronic valve having input and output electrodes coupled through said resonant circuit, said output electrodes being connected to said terminals, thereby forming a source of periodic current for the pump.

References Cited UNITED STATES PATENTS 2,363,478 11/1944 Boeke 230- XR 2,654,324 10/1953 Ryba 103-53 2,809,589 10/1957 Randolph 10353 ROBERT M. WALKER, Primary Examiner.

DONLEY J. STOCKING, Examiner. 

